Steel for railroad rails, wheel tires, plank piles, and other objects



Patented May 28, 1935 UNlTE-D; STATES PATENT OFFICE s'mm. i on RAILROADnma'wnn TIRES, PLANE OBJX'EGTS PILES, AND OTHER No Drawing. Applicationbecemberll. 1931.,

Serial No. 580,500. 1930 This invention relates to a steel suitable forobjects subjected to heavy wear.

The following fundamental requirements have to be met in the case ofrailroad rails:

1. The rails must have such a great mechanical strength that they areable to furnish sufficient resistance to stresses during service causedby wheel pressure, shocks and the like. For this purpose an adequatelyhigh elastic limit is neces-- sary, in order .to avoid the railsspreading under the wheel pressure, moreover an adequately highresistance to repeated shock stresses is also required, that is to say,a high resistance to impact stresses and prolonged stresses. Experiencehas 15: shown that these requirements were first met by steels having ahigh elastic limit and good toughness together with a moderate tensilestrength. 2. The resistance to wear of the rails must be so great, thatthe least possible loss due to wear takes place under the action of therolling and sliding friction of the wheels travelling thereover.-

is furnished by the examination under the specification for thecontract. This examination also extends to ascertaining whether thesteel possesses adequate resistance to impact by. means of the railimpact test and proving whether thesteel is sumciently hard and strongmechanically by measuring the Brinell hardness or by means of thedraw-test.

It is difficult to fulfil these manifold requirem'ents-withoutdetrimentally aifecting the other properties to a certain extent. Therequirements as regards high toughness together with high mechanicalstrength counteract one another to a certain extent. The requirement asregards high resistance to wear cannot be attained in view of theforegoing two criteria, since resistance to wear does not run parallelin any way to hardness, elastic limit or tensile strength. 50 It istherefore a question in view of the practical requirements of the caseunder consideration to evolve an optimum hardness, elastic limit,toughness and resistance to wear with the maximum economy. The means ofeffecting this are various. It is well known that the-tensile strengthIn Germany December 12, 2 Claims. (01.75-1) and elastic limit may beincreased by increasing the carbon content, the 'manganese content, thesilicon content and also by the addition of other elementssuchaschromium, nickel and the like, the latter however not coming intoconsideration 5 in the present casefor' economic reasons.

It is also known that increasing the content of manganese and also thatof phosphorus increases the resistance to wear. Nevertheless aconsiderable increase in practice of the resistance to wear can only beproduced. by adding manganese in v such quantities that the toughness(determined by the elongation during thefracture test, behaviour duringthe impact test and the notch-bar toughness) begins to decrease toorapidly. Hitherto no use at all could .be made of the effect of thephorphorus increasing the resistance to wear,

. since, in the usual composition of the rails hav-' ing phosphoruscontents below about 0.08% practically no noticeable influence occursand any increase of the phosphorus content above 0.1%

renders the rails too brittle, that is to say, too

sensitive to shocks. For these reasons hitherto the steel works kept thephosphorus content at about 0.08% as the upper limit. I

Tests made by the applicant have now shown that the property ofphosphorus of increasing the resistance to wear of these steels can bemade possible by adding this element in quantities of 0.08% and more andat the same time considerably reducing the carbon content .blows usuallyafter sagging to the extent of more than 140 ms. The elastic limit issufllciently h, being more than 36 kg. per mm., to avoid the railsspreading even when the wheel pressure is increased and the elongationand the notchbar-toughness are of such a high order that there is nodanger of the rail being affected detrimentally by impact or shocks. Theresistance to wear is increased to such a great extentby the combinedaction of manganese and phosphorus, that this steel can be compareddirectly with the steel rails which are known to be resistant to wearand which possess a tensile strength of more than 2 '15 kg. per mm., theelongation however and in melts are given in the following table.

particular the notch-bar toughness of the steel or the present inventionbeing greater than in the ordinary steel for rails having thisstrength.In order to bring about'this object it is necessary-to keep the carboncontent low and it possible below 0.20%, the manganese content beingkept within. the limit of about 0.6 to 1.6% and the phosphorus beingabove 0.08% up to about 0.25% whilst the silicon content amounts tobetween 0.1% and 0.6% and the copper content to about 0.25 to 1.0%

By said small content or copper the uniiormity of the structure and themechanical strength properties oi this steel is increased. The coppercontent as is known also increases the resistance to corrosion andrusting oi the steel, whichis of considerable importance in service whenthe steel is used in the presence of corrodve media for example when therails are laid in tunnels.

The steel may contain in addition thereto the usual accompanyingelements, but i! sulphuris present the content thereof shall bepreferably kept low so as to lie from trace to about 0.12%.

Thebal ceoithealloyconsistssubstantially of iron. It may be possible,however, to use some further alloying additions in known quantities andfor known purposes. Such further alloying elements are comprised by theterm the balance substantially iron"; provided, however, that thecharacter of the alloy as described is not materially altered by suchiurtheradditions and that the elements mentioned are present in theamounts specified.

The tensile strength properties and the resist- .ance to wear of suchrails were determined exhaustively from a large number of melts, theapparatus oi. Spindel and Mohr and liederhaii being employed fordetermining the resistance to wear.

Examples oi. the results of several tests on railTheimpacttestprescribedbytheqerman State Railway in their specificationfor steel was passed by'these rails altogether in a very satisfactorymanner, and even when this test was made more stringent, fracture onlyoccurred after ordinary carbon rails having a tensile strength of 70mkg.per sq. mm. had already broken underthe test. As' may moreover be seenfrom the tablere'sistanoe to wear is also considerably higher than thatoi. other rails oi' the.

same mechanical strength, values beingv shown whichare only obtainablein carbon steel rails ha atensiiestrengthofaboutfikgperwhenconsiderin'gtheresultsoitheweartest on the Mohr and l 'ederhailmachines it should be mentioned that from experience rails having adecrease in-wei'ght duringthe testoi less than 1.1 grams are termed"wear resistant. The rails. produced according to the process of thepresent invention exhibit throughout a 'decrease in weight 0! below 1.1gram.

The permanent resistance'to bending which is also important forpractical service was ascertainedbymeansota'plursiityoi'testsontheSchenck permanent bending machine, Imder loadsoiatleast30kg.persq.mn1.andonthe lngtestpfeceswhieh weresubmittedtotwists, valueshigher than 27kg. per sq. mm. were invariably obtained. Ll'he steel thusvery .highpermanentstrengthatthesametimevery Tsnnn 'CoMosia'onandotrsngthpropsflissoIrafleSN .M I! m WM Stool v I W s Mob:Elastic mm. M Notched $111 and 0 Guile limit mu m tenacity 0!. mm Lcutln' deans.

Pcr- Pa- Per- Pcr- Per- Per i...- Per on out can! seat rent out Kflmmw.Buoyant. out eel Analog-am. llsu. Grass 1.- 0 3011 0.00 0.02 0.14 0.0a002 :1 01 1s 1s a 4: 1.4 (Com 0.42 0.15 0.00 000 0.00 40 1s 1s 10 2 411.1 son.

r-g n 0.11 0.00 1.00 0.11 0100' it "o1 24 to s an 0.0

S 4 0.01 0.21? 1.02 000 0.40 0.0 u as as s: 11 as as 014 040 120 0.100.40 4s 02 10 v u s as 4 0.1; 0 010 040 0.18 0.40- is 02. 11 4s 0 a1 0.1012 0.40 1.90 1; 050 0.10 42 so as as s .40 0.0

l'ormoitestpiece l0x10x00witbacircularnotch5 mms. deep-2m. eLengtholcutasthea 0 din cutsunderapressure'oiiikgs.,260completomolutionsn=25.

1 Decrease alter 200,000 revoiutions n n dsr an applied prsssurs'oi 100kgs.; 1% slip, 425 pa minute.

' In spite of the relatively low carbon content content was in to'over0.1%, the silicon the elastic limit oi! the steel is above 40 kg. persq. mm., 1. e. it possesses values which could only be produced in anordinary steel having-a carbon content of more than 0.5%.

average of 34 kg. per sq. mm. Even when testcontent being increased atthe sametlme. The

tires plank-pilesnnd particularly for sea walls 7 and other steel partswhichare subjected to wear. 1 Having-now aseer-' tained the nature of mysaid invention-and in what manner the same is to be performed, I declarethat what I claim is:

1. A steel for railroad rails, wheel tires, plank- 'piles and otherobjects which are subjected to heavy wear, said steel containing about0.05 to 0.20% of carbon, about 0.08 to 0.25% of phosphorus, about 0.1 to0.6% of silicon, about 0.6 to 1.6% of manganese and about 0.25 to 1% ofcop- 10 per and the balance substantially iron.

2. A steel for railroad rails, wheel tires, plankpiles and otherobjects, which are subjected to heavy wear, with a sulphur content offrom trace to about 0.12%, said steel containing about 0.05 to 0.20% ofcarbon, about 0.08 to 0.25% phosphorus, about 0.1 to 0.6% of silicon,about 0.6 to 1.6% of manganese and about 0.25 to 1% o! copper, thebalance consisting substantially of iron.

HERBERT BUCHHOLTZ.

